ChinesePod - Live from Taiwan
Learn Chinese on your terms and at your own pace by taking out an inexpensive subscription with ChinesePod.
Allows you to download daily podcasts geared to a range of levels from complete newbie to advanced
student. Engaging and enthusiastic presenters make each lesson a pleasure.

Skritter
This is a fantastic online resource for learning characters by drawing them with your mouse or writing tablet.
Tracks your progress and presents you with daily tests.

Anki
Anki is a free, super-flexible flash card program which is fully compatible with a
wide range of hand held devices including iPod Touch and Windows CE.

CC-CEDICT
This is the plug-in Chinese-English dictionary that Character Mine uses.
CC-Cedict is a wiki style collaborative effort, with users providing entries and corrections to the main file.
It is licensed under a Creative Commons Attribution-Share Alike 3.0 Licence.

Chinese Perapera-kun
If you don't use Mozilla Firefox it is worth installing it just to get this free add-on. Allows
you to browse Chinese web pages with the help of a mouse-over pop-up translation engine.

ZDT (Zhongwen Development Tool) Language Learner
The ZDT (Zhongwen Development Tool) is an easy to use, open-source Mandarin Chinese flashcard application
that can help you learn Chinese.
This is an open source project that will be of special interest to Java developers.